1. Field of the Invention
The present invention relates to a fan with a heat sink and, more particularly, to a fan having a heat sensor which extends to a heat sink so as to detect the precise temperature of the sink and enable the rotational speed of the air impeller to be adjusted upon the change of the temperature.
2. Description of Related Art
A speed adjustable fan provided with a speed control circuit of a printed circuit board and a heat sensor attached thereto is known. The printed circuit board is arranged in a parallel configuration with a frame while the heat sensor detecting ambient temperature at an air outlet. Moreover, the heat sensor is capable of extending to a heat source of an operative system to thereby detect the temperature generated thereon.
As shown in FIG. 1, the fan 1 includes a frame 10 defining an air inlet 11 and an air outlet 12, with an air impeller (not numbered) received in the frame 10 between the inlet 11 and the outlet 12. Furthermore, the fan 1 is provided with a heat sensor 13 that extends in a manner parallel to the frame 10 at the air outlet 12 in order to detect the ambient temperature where the sensor 13 is disposed.
Whenever the temperature becomes higher or lower, the heat sensor 13 generates a signal which adjusts the rotational speed of the air impeller corresponding to the detected temperature, i.e. makes the speed faster or slower in response to the change of the ambient temperature around the sensor 13.
With the conventional fan, however, a problem rises that the rotational speed of the air impeller can not be adjusted to meet a excellent speed necessary for a heat source to be blown on, because the heat sensor 13 can not detect the precise temperature of the heat source but the ambient temperature of airflow at the outlet 12 of the frame 10.
The object of the present invention is to provide a fan having a heat sensor arranged below a hub of an impeller proximal a heat source to thereby detect the precise temperature.
Another object of the present invention is to provide a fan having a heat sensor arranged below a hub of an impeller through a sensing aperture proximal a heat source which is simplified both in manufacture and in assembly.
The present invention provides a fan having a heat sensor adapted to detect the precise temperature of a heat source to be blown on. The inventive fan includes a frame, an air impeller and a heat sensor. The frame accommodates the rotary air impeller. The heat sensor is positioned below a hub of the air impeller and extends to an area proximal the heat source, so as to detect the precise temperature and thereby adjust the rotational speed of the air impeller up on the change of the temperature.